Cover photo for John Canty Dempsey's Obituary
John Canty Dempsey Profile Photo
1925 Jack 2023

John Canty Dempsey

September 8, 1925 — November 17, 2023


John “Jack” Canty Dempsey of Frederick, Maryland, passed away at home on Friday, November 17, 2023.  

He was born in Bradford, Pennsylvania on September 8, 1925, to Earl Francis and Ella Bernice (Mackowski) Dempsey of Warsaw, New York.  At the age of 12, Jack started to work for his Uncle Len, the proprietor of a small grocery store, in Limestone, New York where he spent his childhood.  He graduated from Limestone High School in 1943 and enlisted in the Navy at age 18 and supported the WWII effort at Glenview Naval Air Station in Illinois.  He was sent to the University of Oklahoma for officer training. The war ended while still in training.  He chose to be discharged after completing his coursework.  He was a U.S. Navy Veteran.

After graduating with a B.S. in Petroleum Engineering, Jack attended the seminary at St. Bonaventure in Olean, New York.  While attending the seminary, Jack worked as a lifeguard at Allegheny State Park.  He left the seminary to work in the oil industry for Birdwell Corp. and met his bride-to-be, Helena Elizabeth Duhan, of Salamanca, New York while fishing in Allegheny State Park. They married in May 1952 and started their family in Bradford, Pennsylvania.  

The young family, now with four girls, moved to Maryland in the late 1950's where Jack took a position with the Atomic Energy Commission (AEC), and they welcomed three more babies.  He worked as an engineer for the AEC until 1967 when he transferred to a position with the International Atomic Energy Agency (IAEA).  He and Helena took their seven children to Vienna, Austria, for nearly two years.  They moved back to Maryland where Jack continued working with the AEC, which later became the U.S. Department of Energy. He worked there until retirement at age 55.

After retiring from federal service in 1980, Jack and Helena, with their youngest, Kathleen, who was in high school, moved to western New York State. They were near their home of origin where Jack took a position as a Consultant - Nuclear Engineer on dealing with nuclear waste from a retired nuclear plant.  

In 1986, Jack and Helena returned to Frederick where he co-founded Rad Elec, Inc.  He was Vice President of Operations focusing on the Research and Development of the Electret, a radon measurement device co-invented with his colleague and friend, the late Paul Kotrappa, PhD.  Jack continued to provide consultation with Rad Elect into the early 2000's.  Jack was proud of his invention, the Electret.  He knew it was a lasting good that he gave to the world.

Jack was widowed when Helena died in January 2000.  Being an avid reader of the Washington Post, Jack read a personal ad placed by Celia Hahn.  They met and were married in June 2001.  Jack enjoyed Celia’s companionship for over a decade.
A spiritual Catholic, Jack was a member of the St. Katharine Drexel Parish after it was established and a member of the St. John’s Parish since moving to Frederick with a still growing family in 1961.  He wore his faith gently and constantly read writings of contemporary spiritual thinkers for his own spiritual growth.

Physically, Jack was a daily exerciser.  He loved swimming for exercise into his 90's.  He was active in downhill and cross-country skiing into his late 80's.  Jack enjoyed fly-fishing with his brother, Dick.  He planned family camping trips and later rallied friends and their families to embark on week-long camping expeditions over several summers.  He was disciplined in his vitamin and activity regiment.

Jack was preceded in death by his parents; his three brothers, William, Richard, and Donald; his loving wife, Helena; and his second wife, Celia Hahn, of Washington, D.C.  

He is survived by his two sisters-in-law, Dorine (Smith) and Nancy (O’Neil); and his seven adoring children and their spouses, Mary Elizabeth and husband, Thomas Simons, Christine, Carol Ann and husband, Bill Coffman, Bernadette, Suzanne and husband, John Piper, John Mark and wife, Eileen (Macauley), and Kathleen and husband, Gregory Borek. Blessed to call Jack “Beaupa” are 20 grandchildren, Erin, Alan, Audrey, Herbert, Nathan, Joshua, Alysha, Tyler, Hannah, Chelsea, Gideon, Angela, Monica, Allison, Jack, Patrick, Travus, Jordan, Madeline, and Johnathan.  Jack enjoyed 20 “greats” or great-grandchildren, as well as two yet to be born in early January.

Jack’s family is hosting a viewing from 6 to 8:30 p.m. on Thursday, November 30, 2023 at Stauffer Funeral Home, 1621 Opossumtown Pike, Frederick, MD 21702.  A prayer service will begin at 6:30 p.m. Thursday followed by opportunities for those in attendance to share memories. 

A Mass of Christian Burial will be held at 11 a.m. on Friday, December 1, 2023 at St. Katharine Drexel Catholic Church, 8428 Opossumtown Pike in Frederick with Rev. Keith Boisvert as Celebrant. The family would like to invite all attendees to a luncheon in the parish hall immediately following services.  A private inurnment will be held in Resthaven Memorial Gardens, Frederick at a later date. 

In lieu of flowers, consider donating to Meals on Wheels, Frederick County Division of Aging and Independence, 1440 Taney Ave., Frederick, MD  21702.  Our Dad really liked those meals!  

To order memorial trees or send flowers to the family in memory of John Canty Dempsey, please visit our flower store.

Service Schedule

Past Services


Thursday, November 30, 2023

6:00 - 8:30 pm (Eastern time)

Stauffer Funeral Home-Frederick

1621 Opossumtown Pike, Frederick, MD 21702

Enter your phone number above to have directions sent via text. Standard text messaging rates apply.


Friday, December 1, 2023

11:00am - 12:00 pm (Eastern time)

St. Katharine Drexel Catholic Church

8428 Opossumtown Pike, Frederick, MD 21702

Enter your phone number above to have directions sent via text. Standard text messaging rates apply.


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